TOVS PATHFINDER SOFTWARE

In order to read the TOVS data files, the HDF library must be installed on your machine. The HDF application software is available at no cost from the National Center for Supercomputer Applications (NCSA) at the University of Illinois and the Goddard DISC. Although the DISC site is mirrored off the NCSA, the DISC houses pre-compiled HDF libraries and supporting command line executable programs for many UNIX machines. The command line utilities operate directly on HDF files and the HDF library module can be linked to user-written Fortran and C programs which include HDF subroutine calls.

To obtain the HDF library, log into the Goddard DISC's anonymous ftp server using the command:

ftp disc.gsfc.nasa.gov
Name (disc.gsfc.nasa.gov:): anonymous
Password: < your e-mail address >
cd pub/hdf

The README file you have transferred to your system details the structure of the GDISC `hdf' directory and information on downloading the current release of the HDF source code library, currently HDF3.3r4, or if you prefer, the pre-compiled HDF library appropriate to your machine. Read this carefully to determine what files you should download for your particular purpose, then log back into the ftp server and issue the appropriate transfer commands to obtain these files.

If you have any questions or comments at all concerning these libraries, please send e-mail to :
hdf-help-disc@listserv.gsfc.nasa.gov

Or call the DISC help desk at (301) 614-5224.

A sample session which illustrates how to extract information from a TOVS Path A HDF file using the command line utility 'hdfed' (automatically created upon installation of the HDF software) is shown in the Appendix.

Collage

The NCSA has produced a variety of HDF visualization tools that display HDF files containing Scientific Data Sets (SDS). The most popular and versatile package at this time is called Collage. To obtain the program, log into the NCSA anonymous ftp server using the command :

ftp ftp.ncsa.uiuc.edu (or ftp 141.142.3.135)
Name (141.142.3.135:): anonymous
Password: <your e-mail address>
cd /Visualization/Collage

Here you find the versions of Collage for the Macintosh, Unix and PC (Windows) machines. For example, to obtain the `DEC Alpha' Unix version of Collage, type :

cd Unix/Collage1.3

Then set the transfer mode to "binary" and download the required file. Make sure that you have sufficient disk space on your local machine. For example, a minimum of about 2.3 Mbytes of space is needed in this case:

ftp> binary
ftp> get collage.alpha.gz

Next download the instructions required to install and use Collage:

ftp> get DOCS
ftp> bye

The ".gz" suffix on the file indicates that a special form of storage has been used (called "compression") to temporarily store the file in such a way as to conserve disk space. The file must be "uncompressed" and the file protection changed before attempting to use it by issuing the following Unix commands :

gunzip collage.alpha.gz
chmod 755 collage.alpha

Use the information in DOCS to become acquainted with the operation and applications of Collage.

At some point you may want to log back into the NCSA through anonymous ftp and retrieve the detailed User's Guide for Collage. However, be aware that this file is very large, close to 62 MBytes compressed. If you do not have sufficient space to download the User's Guide to your machine, please contact the Goddard DISC help desk at the phone number listed in the previous section in order to obtain a hardcopy version of the Guide.

VISTAS

In addition, a visualization package called VISTAS has been developed by a group at JPL and designed specifically for use with the level 3 TOVS Pathfinder data. VISTAS allows users to "navigate" the data by specifying which parameters they would like to visually examine on a certain date. They will be able to perform basic image processing functions and animation capabilities that make use of zooming and scrolling around the data set. Enhancements are planned in later releases of VISTAS. Currently, VISTAS runs on Sun Sparc Stations using Sun Operating Systems (OS) 4.1.x and on Silicon Graphics Workstations using IRIX 5.1.x. To obtain VISTAS, log into the Goddard DISC anonymous ftp using:

ftp disc.gsfc.nasa.gov or ftp 192.107.190.139
cd /pub/tovs/vistas
get VISTAS.README_FIRST

After obtaining the README, log out of anonymous ftp and consult the README for a detailed description on obtaining, installing and getting help on VISTAS. Please refer to section 6 of this document for a list of contacts for VISTAS software and user support.

Some other public domain and commercial software packages can be used to view HDF data. They are: EASI/PACE, IDL, and SpyGlass (to obtain these, see Section 6). Thus far only IDL has been tested by the DISC for reading and visualizing the TOVS Pathfinder files.